1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "memory/freeBlockDictionary.hpp" 27 #include "memory/freeList.hpp" 28 #include "memory/metachunk.hpp" 29 #include "memory/sharedHeap.hpp" 30 #include "runtime/globals.hpp" 31 #include "runtime/mutex.hpp" 32 #include "runtime/vmThread.hpp" 33 #include "utilities/macros.hpp" 34 35 #if INCLUDE_ALL_GCS 36 #include "gc_implementation/concurrentMarkSweep/freeChunk.hpp" 37 #endif // INCLUDE_ALL_GCS 38 39 // Free list. A FreeList is used to access a linked list of chunks 40 // of space in the heap. The head and tail are maintained so that 41 // items can be (as in the current implementation) added at the 42 // at the tail of the list and removed from the head of the list to 43 // maintain a FIFO queue. 44 45 template <class Chunk> 46 FreeList<Chunk>::FreeList() : 47 _head(NULL), _tail(NULL) 48 #ifdef ASSERT 49 , _protecting_lock(NULL) 50 #endif 51 { 52 _size = 0; 53 _count = 0; 54 } 55 56 template <class Chunk> 57 void FreeList<Chunk>::link_head(Chunk* v) { 58 assert_proper_lock_protection(); 59 set_head(v); 60 // If this method is not used (just set the head instead), 61 // this check can be avoided. 62 if (v != NULL) { 63 v->link_prev(NULL); 64 } 65 } 66 67 68 69 template <class Chunk> 70 void FreeList<Chunk>::reset() { 71 // Don't set the _size to 0 because this method is 72 // used with a existing list that has a size but which has 73 // been emptied. 74 // Don't clear the _protecting_lock of an existing list. 75 set_count(0); 76 set_head(NULL); 77 set_tail(NULL); 78 } 79 80 template <class Chunk> 81 void FreeList<Chunk>::initialize() { 82 #ifdef ASSERT 83 // Needed early because it might be checked in other initializing code. 84 set_protecting_lock(NULL); 85 #endif 86 reset(); 87 set_size(0); 88 } 89 90 template <class Chunk_t> 91 Chunk_t* FreeList<Chunk_t>::get_chunk_at_head() { 92 assert_proper_lock_protection(); 93 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 94 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 95 Chunk_t* fc = head(); 96 if (fc != NULL) { 97 Chunk_t* nextFC = fc->next(); 98 if (nextFC != NULL) { 99 // The chunk fc being removed has a "next". Set the "next" to the 100 // "prev" of fc. 101 nextFC->link_prev(NULL); 102 } else { // removed tail of list 103 link_tail(NULL); 104 } 105 link_head(nextFC); 106 decrement_count(); 107 } 108 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 109 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 110 return fc; 111 } 112 113 114 template <class Chunk> 115 void FreeList<Chunk>::getFirstNChunksFromList(size_t n, FreeList<Chunk>* fl) { 116 assert_proper_lock_protection(); 117 assert(fl->count() == 0, "Precondition"); 118 if (count() > 0) { 119 int k = 1; 120 fl->set_head(head()); n--; 121 Chunk* tl = head(); 122 while (tl->next() != NULL && n > 0) { 123 tl = tl->next(); n--; k++; 124 } 125 assert(tl != NULL, "Loop Inv."); 126 127 // First, fix up the list we took from. 128 Chunk* new_head = tl->next(); 129 set_head(new_head); 130 set_count(count() - k); 131 if (new_head == NULL) { 132 set_tail(NULL); 133 } else { 134 new_head->link_prev(NULL); 135 } 136 // Now we can fix up the tail. 137 tl->link_next(NULL); 138 // And return the result. 139 fl->set_tail(tl); 140 fl->set_count(k); 141 } 142 } 143 144 // Remove this chunk from the list 145 template <class Chunk> 146 void FreeList<Chunk>::remove_chunk(Chunk*fc) { 147 assert_proper_lock_protection(); 148 assert(head() != NULL, "Remove from empty list"); 149 assert(fc != NULL, "Remove a NULL chunk"); 150 assert(size() == fc->size(), "Wrong list"); 151 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 152 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 153 154 Chunk* prevFC = fc->prev(); 155 Chunk* nextFC = fc->next(); 156 if (nextFC != NULL) { 157 // The chunk fc being removed has a "next". Set the "next" to the 158 // "prev" of fc. 159 nextFC->link_prev(prevFC); 160 } else { // removed tail of list 161 link_tail(prevFC); 162 } 163 if (prevFC == NULL) { // removed head of list 164 link_head(nextFC); 165 assert(nextFC == NULL || nextFC->prev() == NULL, 166 "Prev of head should be NULL"); 167 } else { 168 prevFC->link_next(nextFC); 169 assert(tail() != prevFC || prevFC->next() == NULL, 170 "Next of tail should be NULL"); 171 } 172 decrement_count(); 173 assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0, 174 "H/T/C Inconsistency"); 175 // clear next and prev fields of fc, debug only 176 NOT_PRODUCT( 177 fc->link_prev(NULL); 178 fc->link_next(NULL); 179 ) 180 assert(fc->is_free(), "Should still be a free chunk"); 181 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 182 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 183 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 184 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 185 } 186 187 // Add this chunk at the head of the list. 188 template <class Chunk> 189 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk, bool record_return) { 190 assert_proper_lock_protection(); 191 assert(chunk != NULL, "insert a NULL chunk"); 192 assert(size() == chunk->size(), "Wrong size"); 193 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 194 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 195 196 Chunk* oldHead = head(); 197 assert(chunk != oldHead, "double insertion"); 198 chunk->link_after(oldHead); 199 link_head(chunk); 200 if (oldHead == NULL) { // only chunk in list 201 assert(tail() == NULL, "inconsistent FreeList"); 202 link_tail(chunk); 203 } 204 increment_count(); // of # of chunks in list 205 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 206 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 207 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 208 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 209 } 210 211 template <class Chunk> 212 void FreeList<Chunk>::return_chunk_at_head(Chunk* chunk) { 213 assert_proper_lock_protection(); 214 return_chunk_at_head(chunk, true); 215 } 216 217 // Add this chunk at the tail of the list. 218 template <class Chunk> 219 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk, bool record_return) { 220 assert_proper_lock_protection(); 221 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 222 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 223 assert(chunk != NULL, "insert a NULL chunk"); 224 assert(size() == chunk->size(), "wrong size"); 225 226 Chunk* oldTail = tail(); 227 assert(chunk != oldTail, "double insertion"); 228 if (oldTail != NULL) { 229 oldTail->link_after(chunk); 230 } else { // only chunk in list 231 assert(head() == NULL, "inconsistent FreeList"); 232 link_head(chunk); 233 } 234 link_tail(chunk); 235 increment_count(); // of # of chunks in list 236 assert(head() == NULL || head()->prev() == NULL, "list invariant"); 237 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); 238 assert(head() == NULL || head()->size() == size(), "wrong item on list"); 239 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); 240 } 241 242 template <class Chunk> 243 void FreeList<Chunk>::return_chunk_at_tail(Chunk* chunk) { 244 return_chunk_at_tail(chunk, true); 245 } 246 247 template <class Chunk> 248 void FreeList<Chunk>::prepend(FreeList<Chunk>* fl) { 249 assert_proper_lock_protection(); 250 if (fl->count() > 0) { 251 if (count() == 0) { 252 set_head(fl->head()); 253 set_tail(fl->tail()); 254 set_count(fl->count()); 255 } else { 256 // Both are non-empty. 257 Chunk* fl_tail = fl->tail(); 258 Chunk* this_head = head(); 259 assert(fl_tail->next() == NULL, "Well-formedness of fl"); 260 fl_tail->link_next(this_head); 261 this_head->link_prev(fl_tail); 262 set_head(fl->head()); 263 set_count(count() + fl->count()); 264 } 265 fl->set_head(NULL); 266 fl->set_tail(NULL); 267 fl->set_count(0); 268 } 269 } 270 271 // verify_chunk_in_free_lists() is used to verify that an item is in this free list. 272 // It is used as a debugging aid. 273 template <class Chunk> 274 bool FreeList<Chunk>::verify_chunk_in_free_list(Chunk* fc) const { 275 // This is an internal consistency check, not part of the check that the 276 // chunk is in the free lists. 277 guarantee(fc->size() == size(), "Wrong list is being searched"); 278 Chunk* curFC = head(); 279 while (curFC) { 280 // This is an internal consistency check. 281 guarantee(size() == curFC->size(), "Chunk is in wrong list."); 282 if (fc == curFC) { 283 return true; 284 } 285 curFC = curFC->next(); 286 } 287 return false; 288 } 289 290 template <class Chunk> 291 void FreeList<Chunk>::assert_proper_lock_protection() const { 292 #ifdef ASSERT 293 // Nothing to do if the list has no assigned protecting lock 294 if (protecting_lock() == NULL) { 295 return; 296 } 297 298 Thread* thr = Thread::current(); 299 if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) { 300 // assert that we are holding the freelist lock 301 } else if (thr->is_GC_task_thread()) { 302 assert(protecting_lock()->owned_by_self(), "FreeList RACE DETECTED"); 303 } else if (thr->is_Java_thread()) { 304 assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing"); 305 } else { 306 ShouldNotReachHere(); // unaccounted thread type? 307 } 308 #endif 309 } 310 311 // Print the "label line" for free list stats. 312 template <class Chunk> 313 void FreeList<Chunk>::print_labels_on(outputStream* st, const char* c) { 314 st->print("%16s\t", c); 315 st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" 316 "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n", 317 "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep", 318 "count", "cBirths", "cDeaths", "sBirths", "sDeaths"); 319 } 320 321 // Print the AllocationStats for the given free list. If the second argument 322 // to the call is a non-null string, it is printed in the first column; 323 // otherwise, if the argument is null (the default), then the size of the 324 // (free list) block is printed in the first column. 325 template <class Chunk_t> 326 void FreeList<Chunk_t>::print_on(outputStream* st, const char* c) const { 327 if (c != NULL) { 328 st->print("%16s", c); 329 } else { 330 st->print(SIZE_FORMAT_W(16), size()); 331 } 332 } 333 334 template class FreeList<Metablock>; 335 template class FreeList<Metachunk>; 336 #if INCLUDE_ALL_GCS 337 template class FreeList<FreeChunk>; 338 #endif // INCLUDE_ALL_GCS